The objective of this research is to understand the functional mechanism used by mammals, as exemplified by the cat, to process neural information regarding movement of images. We have developed methods that utilize computer controlled stimulus presentation and on-line analysis of neural responses to measure precisely firing rates and spatial receptive field properties of responses. By interleaving presentations of both stationary and smoothly moving stimuli we expect to minimize the differential effects of spontaneous fluctuations in excitability and eye position in order to establish the dependence of movement elicited responses on spatial and temporal properties of statically elicited responses. We will also investigate mechanisms underlying selectivity in direction of movement by means of stepwise stationary presentations that elicit directionally selective responses yet allow identification of spatially static excitatory and inhibitory phases of the stimulus. Using appropriately placed electrodes in the lateral geniculate nucleus and in the cortex we intend to study geniculo-cortical synaptic connections by means of recently developed cross-correlation techniques applied to simultaneous smooth movement elicited responses. These techniques provide information on strength and sign of synaptic connections and will elucidate the dependence of cortical receptive field organization on input from different types of units in the lateral geniculate. BIBLIOGRAPHIC REFERENCES: Emerson, R. C. and G. L. Gerstein. 1977. Simple striate neurons in the cat. I. Comparison of responses to moving and stationary stimuli. J. Neurophysiol. 40:119-135. Emerson, R. C. and G. L. Gerstein. 1977. Simple striate neurons in the cat. II. Mechanisms underlying directional asymmetry and directional selectivity. J. Neurophysiol. 40:136-155.